as in treacherous
formal
causing harm in a way that is gradual or not easily noticed
Most people with this insidious disease have no idea that they are infected. an insidious enemy
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Example Sentences
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Recent Examples of insidious
Complicating matters is the insidious Host character (voiced by Len Cunningham’s father, Liam Cunningham), who manipulates the players’ reality.
—
Jennifer Maas, Variety, 2 Oct. 2025
But the long-term story is more insidious.
—Bill Frist, Forbes.com, 18 Sep. 2025
And that’s especially true when a demon as insidious as Doma or brutal as Akaza steps into frame (special shout-out to the deliciously cruel and twisted sympathy Doma shares for his opponent Shinobu Kocho during their fight).
—David Opie, IndieWire, 10 Sep. 2025
This in our view is the insidious threat social media and rapidly growing AI capabilities pose to society and culture.
—The Editorial Board, Chicago Tribune, 31 Aug. 2025
See All Example Sentences for insidious
Jennifer Maas, Variety, 2 Oct. 2025
But the long-term story is more insidious.
—Bill Frist, Forbes.com, 18 Sep. 2025
And that’s especially true when a demon as insidious as Doma or brutal as Akaza steps into frame (special shout-out to the deliciously cruel and twisted sympathy Doma shares for his opponent Shinobu Kocho during their fight).
—David Opie, IndieWire, 10 Sep. 2025
This in our view is the insidious threat social media and rapidly growing AI capabilities pose to society and culture.
—The Editorial Board, Chicago Tribune, 31 Aug. 2025
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
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Residents who live in the snow belts should prepare for treacherous driving conditions and near-zero visibility at times through early Tuesday.—
Joe Edwards,
MSNBC Newsweek,
10 Nov. 2025
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As the first snowstorm of the season fell throughout the province of Ontario, Atletico Ottawa and Cavalry FC competed through treacherous snow and blizzard-like conditions in front of 13,132 fans, making for a remarkable Canadian Premier League Final.—
Joshua Kloke,
New York Times,
10 Nov. 2025
Adjective
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There are more subtle links between the franchises as well, like the casting of Cameron Brown as the Drone Synth in the film.—
Lauren Huff,
Entertainment Weekly,
8 Nov. 2025
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Lucky Step Platform Sneakers These brown suede platform sneakers give a subtle lift while staying super comfortable thanks to memory foam insoles and arch support.—
Chaise Sanders,
Travel + Leisure,
8 Nov. 2025
Adjective
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The title-winning standard has been lower in recent years; City won it with 86, 93, 89 and 91 points between 2020-21 and 2023-24 and Liverpool with 84 points last season, but some of those totals give a false impression.—
Oliver Kay,
New York Times,
8 Nov. 2025
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The month prior, she was sentenced to one year and nine months in prison for using marijuana while owning a firearm and making false statements about drug use, per the newspaper.—
Christopher Rudolph,
PEOPLE,
8 Nov. 2025
Adjective
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The lawsuit, filed in New York federal court on Tuesday, brings claims for deceptive practices and false advertising, among others.—
Winston Cho,
HollywoodReporter,
5 Nov. 2025
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The complaints allow the public to report unfair or deceptive business practices, according to the agency’s website, and can prompt investigations from the office.—
Nicole Blanchard,
Idaho Statesman,
3 Nov. 2025
Adjective
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Her Ashley is the movie’s fourth and fifth wheel, dismissed as both a perfidious troublemaker and a New Age airhead—a life coach in need of a wife coach.—
Justin Chang,
New Yorker,
22 Aug. 2025
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This perfidious situation, unintentional as its creation may have been, was strongly critiqued as far back as 1983 by Jonathan Crush and Paul Wellings in an article in The Journal of Modern African Studies.—
The Editors,
JSTOR Daily,
15 Aug. 2025
Adjective
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Using incorrect or false case references in legal documents has real implications for defendants, because judges rely on these references to help form their rulings, Kjoller’s lawyers wrote.—
Sharon Bernstein,
Sacbee.com,
7 Nov. 2025
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Appeals can be made based on factors including incorrect data, adverse testing conditions, and school or community emergencies, according to the State Board of Education.—
Erick Trevino,
AZCentral.com,
5 Nov. 2025
Adjective
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As analysis, that’s not wrong, but where’s the sting of it inside this bizarre bonbon of a musical?—
Sara Holdren,
Vulture,
10 Nov. 2025
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Despite his brilliance and intellect, he was prevented from having a full life by being born on the wrong side of Israel’s separation fence.—
Literary Hub,
Literary Hub,
10 Nov. 2025
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 14 Nov. 2025.
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